Coated abrasive articles

ABSTRACT

An abrasive article is presented that includes a first set of shaped abrasive particles with a majority of the first set of shaped abrasive particles are oriented with respect to a backing in a first orientation. The abrasive article also includes a second set of shaped abrasive particles with a majority of the second set of shaped abrasive particles are oriented with respect to the backing in a second orientation, and wherein the second orientation differs from the first orientation. The first and second set of shaped abrasive particles are embedded within a coating layer on the baking.

BACKGROUND

Coated abrasive articles containing shaped abrasive grains are usefulfor shaping, finishing, or grinding a wide variety of materials andsurfaces such as wood, metals (e.g., especially non-ferrous metals suchas aluminum that tend to clog grinding wheels), and flash.

Coated abrasive articles having rotationally aligned triangular abrasiveparticles are disclosed in U.S. Pat. No. 9,776,302 (Keipert). The coatedabrasive articles have a plurality of triangular abrasive particles eachhaving a surface feature. The plurality of triangular abrasive particlesis attached to a flexible backing by a make coat comprising a resinousadhesive forming an abrasive layer. There continues to be a need forimproving the cost, performance, and/or life of coated abrasivearticles.

SUMMARY

An abrasive article is presented that includes a first set of shapedabrasive particles with a majority of the first set of shaped abrasiveparticles are oriented with respect to a backing in a first orientation.The abrasive article also includes a second set of shaped abrasiveparticles with a majority of the second set of shaped abrasive particlesare oriented with respect to the backing in a second orientation, andwherein the second orientation differs from the first orientation. Thefirst and second set of shaped abrasive particles are embedded within acoating layer on the baking.

At least some abrasive articles presented herein provide greater cuttingperformance over the use life.

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentdisclosure. The description that follows more particularly exemplifiesillustrative embodiments. It is to be understood, therefore, that thefollowing description should not be read in a manner that would undulylimit the scope of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top-down schematic of an exemplary coated abrasive article.

FIG. 2 is a schematic cross-sectional view of an exemplary coatedabrasive article.

FIG. 3 is an image of a coated abrasive disc after some wear.

FIG. 4 is a schematic cross-sectional view of a coated abrasive articlein accordance with embodiments described herein.

FIG. 5 illustrates a method of manufacturing a coated abrasive articlein accordance with embodiments described herein.

FIG. 6 is a schematic cross-sectional view of an abrasive articledeposition process for a coated abrasive article.

FIG. 7 is a top down schematic of a coated abrasive article accordancewith embodiments described herein.

FIGS. 8A and 8B illustrated close up views of coated abrasive articles.

FIGS. 9-10 illustrate data discussed in the Examples included herein.

Repeated use of reference characters in the specification and drawingsis intended to represent the same or analogous features or elements ofthe disclosure. It should be understood that numerous othermodifications and embodiments can be devised by those skilled in theart, which fall within the scope and spirit of the principles of thedisclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

Throughout this document, values expressed in a range format should beinterpreted in a flexible manner to include not only the numericalvalues explicitly recited as the limits of the range, but also toinclude all the individual numerical values or sub-ranges encompassedwithin that range as if each numerical value and sub-range is explicitlyrecited. For example, a range of “about 0.1% to about 5%” or “about 0.1%to 5%” should be interpreted to include not just about 0.1% to about 5%,but also the individual values (e.g., 1%, 2%, 3%, and 4%) and thesub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within theindicated range. The statement “about X to Y” has the same meaning as“about X to about Y,” unless indicated otherwise. Likewise, thestatement “about X, Y, or about Z” has the same meaning as “about X,about Y, or about Z,” unless indicated otherwise.

In this document, the terms “a,” “an,” or “the” are used to include oneor more than one unless the context clearly dictates otherwise. The term“or” is used to refer to a nonexclusive “or” unless otherwise indicated.The statement “at least one of A and B” has the same meaning as “A, B,or A and B.” In addition, it is to be understood that the phraseology orterminology employed herein, and not otherwise defined, is for thepurpose of description only and not of limitation. Any use of sectionheadings is intended to aid reading of the document and is not to beinterpreted as limiting; information that is relevant to a sectionheading may occur within or outside of that particular section.

In the methods described herein, the acts can be carried out in anyorder without departing from the principles of the disclosure, exceptwhen a temporal or operational sequence is explicitly recited.Furthermore, specified acts can be carried out concurrently unlessexplicit claim language recites that they be carried out separately. Forexample, a claimed act of doing X and a claimed act of doing Y can beconducted simultaneously within a single operation, and the resultingprocess will fall within the literal scope of the claimed process.

The term “about” as used herein can allow for a degree of variability ina value or range, for example, within 10%, within 5%, or within 1% of astated value or of a stated limit of a range, and includes the exactstated value or range.

The term “substantially” as used herein refers to a majority of, ormostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%,98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or100%.

As used herein, the term “shaped abrasive particle,” means an abrasiveparticle with at least a portion of the abrasive particle having apredetermined shape that is replicated from a mold cavity used to formthe shaped precursor abrasive particle. Except in the case of abrasiveshards (e.g. as described in U.S. Pat. Application Publication Nos.2009/0169816 and 2009/0165394), the shaped abrasive particle willgenerally have a predetermined geometric shape that substantiallyreplicates the mold cavity that was used to form the shaped abrasiveparticle. Shaped abrasive particle as used herein excludes abrasiveparticles obtained by a mechanical crushing operation. Suitable examplesfor geometric shapes having at least one vertex include polygons(including equilateral, equiangular, star-shaped, regular and irregularpolygons), lens- shapes, lune-shapes, circular shapes, semicircularshapes, oval shapes, circular sectors, circular segments, drop-shapesand hypocycloids (for example super elliptical shapes).

For the purposes of this invention, geometric shapes are also intendedto include regular or irregular polygons or stars wherein one or moreedges (parts of the perimeter of the face) can be arcuate (either oftowards the inside or towards the outside, with the first alternativebeing preferred). Hence, for the purposes of this invention, triangularshapes also include three- sided polygons wherein one or more of theedges (parts of the perimeter of the face) can be arcuate. The secondside may include (and preferably is) a second face. The second face mayhave a perimeter of a second geometric shape.

For the purposes of this invention, shaped abrasive particles alsoinclude abrasive particles comprising faces with different shapes, forexample on different faces of the abrasive particle. Some embodimentsinclude shaped abrasive particles with different shaped opposing sides.The different shapes may include, for example, differences in surfacearea of two opposing sides, or different polygonal shapes of twoopposing sides.

The shaped abrasive particles are typically selected to have an edgelength in a range of from 0.001 mm to 26 mm, more typically 0.1 mm to 10mm, and more typically 0.5 mm to 5 mm, although other lengths may alsobe used.

The shaped abrasive particle may have a “sharp portion” which is usedherein to describe either a sharp tip or a sharp edge of an abrasivearticle. The sharp portion may be defined using a radius of curvature,which is understood in this disclosure, for a sharp point, to be theradius of a circular arc which best approximates the curve at thatpoint. For a sharp edge, the radius of curvature is understood to be theradius of the curvature of the profile of the edge on the planeperpendicular to the tangent direction of the edge. Further, the radiusof curvature is the radius of a circle which best fits a normal section,or an average of sections measured, along the length of the sharp edge.The smaller a radius of curvature, the sharper the sharp portion of theabrasive particle. Shaped abrasive particles with sharp portions aredefined in U.S. Provisional Pat. Application Ser. No. 62/877,443, filedon Jul. 23, 2019, which is hereby incorporated by reference.

In the instance that the abrasive particles are precisely-shaped (e.g.,into triangular platelets or conical particles), this effect oforientation can be especially important as discussed in U.S. Pat. Appl.Publ. No. 2013/0344786 A1 (Keipert), incorporated by reference herein.As used herein, the term “alignment” is used to refer to a relativeposition of an abrasive particle on a backing, while the term“orientation” refers to a rotational position of the abrasive particleat the aligned position. For example, a triangle-shaped particle mayhave a “tip up” orientation or a “tip down” orientation with respect tothe backing.

As used herein, the term shaped abrasive particle refers to a monolithicabrasive particle. As shown, shaped abrasive particle is free of abinder and is not an agglomeration of abrasive particles held togetherby a binder or other adhesive material.

FIGS. 1 and 2 show an exemplary coated abrasive disc 100 according tothe present disclosure, wherein shaped abrasive particles 130 aresecured at precise locations and Z-axis rotational orientations to abacking 110. In one embodiment, shaped abrasive particles 130 aretriangular prism shaped particles that appear rectangular when viewedfrom above.

Generally, a coated abrasive article 100 includes a plurality ofabrasive particles embedded within a make coat that secures theparticles to a backing. The backing may be formed from any knownflexible coated abrasive backing, for example. Suitable materials forthe backing include polymeric films, metal foils, woven fabrics, knittedfabrics, paper, nonwovens, foams, screens, laminates, combinationsthereof, and treated versions thereof.

The abrasive particles 130 may be embedded within an abrasive layer,which can include multilayer construction having make 120 and sizelayers 140. Coated abrasive articles according to the present disclosuremay include additional layers such as, for example, an optionalsupersize layer that is superimposed on the abrasive layer, or a backingantistatic treatment layer may also be included, if desired. Exemplarysuitable binders can be prepared from thermally curable resins,radiation-curable resins, and combinations thereof.

Make layer 120 can be formed by coating a curable make layer precursoronto a major surface of backing 110. The make layer precursor mayinclude, for example, glue, phenolic resin, aminoplast resin,urea-formaldehyde resin, melamine-formaldehyde resin, urethane resin,free-radically polymerizable polyfunctional (meth)acrylate (e.g.,aminoplast resin having pendant α,β-unsaturated groups, acrylatedurethane, acrylated epoxy, acrylated isocyanurate), epoxy resin(including bis-maleimide and fluorene-modified epoxy resins),isocyanurate resin, and mixtures thereof. Of these, phenolic resins arepreferred.

Phenolic resins are generally formed by condensation of phenol andformaldehyde, and are usually categorized as resole or novolac phenolicresins. Novolac phenolic resins are acid-catalyzed and have a molarratio of formaldehyde to phenol of less than 1:1. Resole (also resol)phenolic resins can be catalyzed by alkaline catalysts, and the molarratio of formaldehyde to phenol is greater than or equal to one,typically between 1.0 and 3.0, thus presenting pendant methylol groups.Alkaline catalysts suitable for catalyzing the reaction between aldehydeand phenolic components of resole phenolic resins include sodiumhydroxide, barium hydroxide, potassium hydroxide, calcium hydroxide,organic amines, and sodium carbonate, all as solutions of the catalystdissolved in water.

Resole phenolic resins are typically coated as a solution with waterand/or organic solvent (e.g., alcohol). Typically, the solution includesabout 70 percent to about 85 percent solids by weight, although otherconcentrations may be used. If the solids content is very low, then moreenergy is required to remove the water and/or solvent. If the solidscontent is very high, then the viscosity of the resulting phenolic resinis too high which typically leads to processing problems.

Phenolic resins are well-known and readily available from commercialsources. Examples of commercially available resole phenolic resinsuseful in practice of the present disclosure include those marketed byDurez Corporation under the trade designation VARCUM (e.g., 29217,29306, 29318, 29338, 29353); those marketed by Ashland Chemical Co. ofBartow, Florida under the trade designation AEROFENE (e.g., AEROFENE295); and those marketed by Kangnam Chemical Company Ltd. of Seoul,South Korea under the trade designation PHENOLITE (e.g., PHENOLITETD-2207).

The make layer precursor may be applied by any known coating method forapplying a make layer to a backing such as, for example, including rollcoating, extrusion die coating, curtain coating, knife coating, gravurecoating, and spray coating.

The basis weight of the make layer utilized may depend, for example, onthe intended use(s), type(s) of abrasive particles, and nature of thecoated abrasive article being prepared, but typically will be in therange of from 1, 2, 5, 10, or 15 grams per square meter (gsm) to 20, 25,100, 200, 300, 400, or even 600 gsm. The make layer may be applied byany known coating method for applying a make layer (e.g., a make coat)to a backing, including, for example, roll coating, extrusion diecoating, curtain coating, knife coating, gravure coating, and spraycoating.

Once the make layer precursor is coated on the backing, the triangularabrasive particles are applied to and embedded in the make layerprecursor. The triangular abrasive particles are applied nominallyaccording to a predetermined pattern and Z-axis rotational orientationonto the make layer precursor. Using known orientation methods, such aselectrostatic or magnetic orientation, it is possible to orient theabrasive particles with respect to the backing in order to improveperformance of the particles.

FIG. 3 illustrates an image of a coated abrasive disc after some wear.Disc 200 has multiple rows 202 of abrasive particles embedded within amake coat 204 on backing 206. As abrasive article 200 is used in anabrading operation, shelling, or unintended removal, of abrasiveparticles occurs, as noted in the comparison of section 220, which stillhas abrasive particles substantially intact, with section 210, which hasexperienced significant shelling and, in some cases, complete removal ofthe make coat, exposing backing 206. However, while disc 200 appears tobe unusable for further abrading operations, because of the experiencedwear in area 210, the disc still has some abrasive life remaining inarea 220. Uneven wear can result for a variety of factors, such as thedifferent velocity experienced by abrasive particles in each of sections210 and 220 during rotation.

It is desired to engineer an abrasive article, such as disc 200, thatexperiences wear more evenly across its diameter, and evencircumferential wear. This may increase overall abrading performance ofan abrasive article, as well as increase an experienced abradingperformance as users are more likely to continue using the abrasivearticle.

FIG. 4 is a schematic cross-sectional view of a coated abrasive articlein accordance with embodiments described herein. An abrasive article 300includes a backing 310, to which a make coat 320 is applied. Abrasiveparticles 330 and 340 are embedded within make coat 320.

The use of precision shaped abrasive grain in abrasive articles hasoften focused on orienting abrasive particles such that a sharp tip isoriented toward a workpiece during an abrading operation. For thisreason, many previous attempts at designing abrasive articles havefocused on increasing a percentage of abrasive particles 330 with a baseedge 334 embedded within a make coat 320 such that an opposing corner332 can abrade a workpiece.

Surprisingly, it has been found that a wear life of an abrasive article300 can be increased by orienting a second set of abrasive particles 340with a different orientation than particles 330. As illustrated in FIG.4 , particles 340 have an orientation opposite those of particles 330.Particles 340 are generally oriented such that a base edge 344 willengage a workpiece and an opposing tip 342 will embed in a make coat.Surprisingly, it was found that the addition of some particles 340 to anabrasive article 300, with a majority of particles being in orientation330, increased the wear life of abrasive article 300 without significantreduction in abrasive performance. While the majority of abrasiveparticles are embedded in an abrading orientation (e.g., in a “tip up”position for a triangular shaped abrasive particle), if a portion of theabrasive particles are embedded in a stabilizing orientation (e.g. in a“tip down” position), the wear life of the abrasive article improved. Insome embodiments, abrasive articles are, therefore, purposefullyembedded in an orientation other the abrading orientation. For example,at least 0.5% of the abrasive particles are in a non-abradingorientation, in one embodiment. In another embodiment, at least 1%, orat least 2%, or at least 3%, or at least 4%, or at least 5%, or at least6%, or at least 7%, or at least 8%, or at least 9%, or at least 10%, orat least 11%, or at least 12%, or at least 13%, or at least 14%, or atleast 15%, or at least 16%, or at least 17%, or at least 18%, or atleast 19%, or at least 20%, or at least 21%, or at least 22%, or atleast 23%, or at least 24%, or at least 25%. In some embodiment, up to30%, 35%, or 40% of abrasive particles are in a non-abradingorientation.

While FIGS. 1-3 describe coated abrasive particles with triangularshaped abrasive particles, it is expressly contemplated that othershapes are possible. For example, rod shaped particles may be present ineither or both of the first and second orientations on the abrasivearticle backing. Additionally, other polygonal prism shapes are alsopossible, in other embodiments. Further, other shapes such astrapezoids, pyramids, cones or truncated pyramids or cones are alsocontemplated.

FIG. 4 illustrates one embodiment where particles 340 are concentratedalong the outer edge of a radius of abrasive article 300. However, it isexpressly contemplated that, in some embodiments, particles 340 arespread across the entire diameter of abrasive article 300. Additionally,while particles 340 are illustrated as filling completely the spacesbetween rows of particles 330, it is expressly contemplated that in someembodiments, particles 340 are present at a lower density than particles330 in a given area of coated abrasive article.

FIG. 5 illustrates a method of manufacturing a coated abrasive articlein accordance with embodiments described herein. Method 400 may be used,for example, to make any of the coated abrasive articles discussedherein. However, it can also be used to make other suitable coatedabrasive articles.

In block 410, a backing is provided. The backing may have apre-treatment prior to the coating process, as indicated in block 402.Pre-treatments may help increase adhesion, reduce shelling, or reducestatic, for example. The provided backing may also be untreated,however, as indicated in block 406. The backing may also have otherfeatures, as indicated in block 408. For example, the backing may beflexible or stiff, and may be made from any suitable woven or nonwovenmaterial.

In block 420, a make coat is provided. The make coat is typicallyprovided in an uncured form such that deposited abrasive particles canembed. The make coat can be deposited on the backing in any number ofsuitable manners including, for example, spray coating, roll-coating,etc.

In block 430, a first set of abrasive particles are embedded within themake coat. The first set of abrasive particles are precision shapedabrasive particles. The first set of abrasive particles may betriangular prisms, as indicated in block 412, rod shaped, as indicatedin block 414, another polygonal shaped prism, as indicated in block 416,or another suitable shape 418. The first set of abrasive particles maybe deposited and oriented on the backing using any suitable method, suchas using electrostatic alignment, as indicated in block 422, whichorients the particles in an X-Y direction, but not in a Z direction.Alternatively, the first set of abrasive particles may be deposited andoriented using magnetic alignment, as indicated in block 424. Forexample, the abrasive particles may include a magnetically responsiveelement or coating such that the particles, when exposed to a magneticfield, will orient in a desired orientation. For example, in oneembodiment the particles orient such that corresponding faces of nearbyparticles are parallel to one another, and such that a sharp tip or edgeis facing away from the backing. Alignment of abrasive particles may beaccomplished using electrostatic coating or magnetic coating, asdescribed in PCT Pat. Appl. Publ. Nos. WO2018/080703 (Nelson et al.),WO2018/080756 (Eckel et al.), WO2018/080704 (Eckel et al.),WO2018/080705 (Adefris et al.), WO2018/080765 (Nelson et al.),WO2018/080784 (Eckel et al.), WO2018/136271 (Eckel et al.),WO2018/134732 (Nienaber et al.), WO2018/080755 (Martinez et al.),WO2018/080799 (Nienaber et al.), WO2018/136269 (Nienaber et al.),WO2018/136268 (Jesme et al.), WO2019/207415 (Nienaber et al.),WO2019/207417 (Eckel et al.), WO2019/207416 (Nienaber et al.), and U.S.Provisional Nos. 62/914,778 filed on Oct. 14, 2019 and 62/875,700 filedJul. 18, 2019, and 62/924,956, filed Oct. 23, 2019.

In some embodiments, the abrasive particles are magnetically responsive.In one embodiment, making particles magnetically responsive includescoating non-magnetically responsive particles with a magneticallyresponsive coating. However, in another embodiment, the particles areformed with magnetically responsive material, for example as recited inco-owned provisional patent U.S. 62/914778, filed on Oct. 14, 2019. Atleast one magnetic material may be included within or coated to shapedabrasive particle. Examples of magnetic materials include iron; cobalt;nickel; various alloys of nickel and iron marketed as Permalloy invarious grades; various alloys of iron, nickel and cobalt marketed asFernico, Kovar, FerNiCo I, or FerNiCo II; various alloys of iron,aluminum, nickel, cobalt, and sometimes also copper and/or titaniummarketed as Alnico in various grades; alloys of iron, silicon, andaluminum (about 85:9:6 by weight) marketed as Sendust alloy; Heusleralloys (e.g., Cu2MnSn); manganese bismuthide (also known as Bismanol);rare earth magnetizable materials such as gadolinium, dysprosium,holmium, europium oxide, alloys of neodymium, iron and boron (e.g.,Nd2Fe14B), and alloys of samarium and cobalt (e.g., SmCo5); MnSb;MnOFe2O3; Y3Fe5O12; CrO2; MnAs; ferrites such as ferrite, magnetite;zinc ferrite; nickel ferrite; cobalt ferrite, magnesium ferrite, bariumferrite, and strontium ferrite; yttrium iron garnet; and combinations ofthe foregoing. In some embodiments, the magnetizable material is analloy containing 8 to 12 weight percent aluminum, 15 to 26 wt% nickel, 5to 24 wt% cobalt, up to 6 wt% copper, up to 1 % titanium, wherein thebalance of material to add up to 100 wt% is iron. In some otherembodiments, a magnetizable coating can be deposited on an abrasiveparticle 100 using a vapor deposition technique such as, for example,physical vapor deposition (PVD) including magnetron sputtering.Including these magnetizable materials can allow shaped abrasiveparticle to be responsive a magnetic field. Any of shaped abrasiveparticles can include the same material or include different materials.

The magnetic coating may be a continuous coating, for example that coatsan entire abrasive particle, or at least coats an entire surface of anabrasive particle. In another embodiment, a continuous coating refers toa coating present with no uncoated portions on the coated surface. Inone embodiment, the coating is a unitary coating - formed of a singlelayer of magnetic material and not as discrete magnetic particulates. Inone embodiment, the magnetic coating is provided on an abrasive particlewhile the particle is still in a mold cavity, such that the magneticcoating directly contacts an abrasive particle precursor surface. In oneembodiment, the thickness of the magnetic coating is at most equal to,or preferably less than, a thickness of the abrasive particle. In oneembodiment, the magnetic coating is not more than about 20 wt.% of thefinal particle, or not more than about 10 wt.% of the final particle, ornot more than 5 wt.% of the final particle.

Magnetically aligning the abrasive particles with respect to each othergenerally requires two steps. First, providing the magnetizable abrasiveparticles described herein on a substrate having a major surface.Second, applying a magnetic field to the magnetizable abrasive particlessuch that a majority of the magnetizable abrasive particles are orientedsubstantially perpendicular to the major surface. Without application ofa magnetic field, the resultant magnetizable abrasive particles may nothave a magnetic moment, and the constituent abrasive particles, ormagnetizable abrasive particles may be randomly oriented. However, whena sufficient magnetic field is applied the magnetizable abrasiveparticles will tend to align with the magnetic field. In favoredembodiments, the ceramic particles have a major axis (e.g. aspect ratioof 2) and the major axis aligns parallel to the magnetic field.Preferably, a majority or even all of the magnetizable abrasiveparticles will have magnetic moments that are aligned substantiallyparallel to one another. As described above, abrasive particlesdescribed herein may have more than one magnetic moment, and will alignwith a net magnetic torque.

The magnetic field can be supplied by any external magnet (e.g., apermanent magnet or an electromagnet) or set of magnets. In someembodiments, the magnetic field typically ranges from 0.5 to 1.5 kOe.Preferably, the magnetic field is substantially uniform on the scale ofindividual magnetizable abrasive particles.

For production of abrasive articles, a magnetic field can optionally beused to place and/or orient the magnetizable abrasive particles prior tocuring a binder (e.g., vitreous or organic) precursor to produce theabrasive article. The magnetic field may be substantially uniform overthe magnetizable abrasive particles before they are fixed in position inthe binder or continuous over the entire, or it may be uneven, or eveneffectively separated into discrete sections. Typically, the orientationof the magnetic field is configured to achieve alignment of themagnetizable abrasive particles according to a predeterminedorientation, for example such that abrasive particles are parallel toeach other and have cutting faces facing in a downweb direction.

Examples of magnetic field configurations and apparatuses for generatingthem are described in U. S. Pat. No. 8,262,758 (Gao) and U. S. Pat. Nos.2,370,636 (Carlton), 2,857,879 (Johnson), 3,625,666 (James), 4,008,055(Phaal), 5,181,939 (Neff), and British (G. B.) Pat. No. 1 477 767(Edenville Engineering Works Limited).

In another embodiment, the abrasive particles are oriented and placedusing a tool, as illustrated in block 426. In some embodiments,patterned drop coating can be achieved using an alignment tool bymethods analogous to that described in PCT Pat. Appl. Publ. Nos.2016/205133 (Wilson et al.), 2016/205267 (Wilson et al.), 2017/007703(Wilson et al.), 2017/007714 (Liu et al.). The method generally involvesthe steps of filling the cavities in a production tool each with one ormore triangular abrasive particles (typically one or two), aligning thefilled production tool and a make layer precursor-coated backing fortransfer of the triangular abrasive particles to the make layerprecursor, transferring the abrasive particles from the cavities ontothe make layer precursor-coated backing, and removing the productiontool from the aligned position. Thereafter, the make layer precursor isat least partially cured (typically to a sufficient degree that thetriangular abrasive particles are securely adhered to the backing), asize layer precursor is then applied over the make layer precursor andabrasive particles, and at least partially cured to provide the coatedabrasive belt. The process, which may be batch or continuous, can bepracticed by hand or automated, e.g., using robotic equipment. It is notrequired to perform all steps or perform them in consecutive order, butthey can be performed in the order listed or additional steps performedin between. The triangular abrasive particles can be placed in thedesired Z-axis rotational orientation formed by first placing them inappropriately shaped cavities in a dispensing surface of a productiontool arranged to have a complementary rectangular grid pattern, or othersuitable pattern based on the shape of the abrasive particles.

Transfer coating using a tool having patterned cavities can be analogousto that described in U.S. Pat. Appln. Publ. No. 2016/0311081 A1 (Culleret al.). In some embodiments, abrasive particles can be applied onto themake layer through a patterned mesh or sieve.

In block 440, a second set of abrasive particles are embedded within themake coat. The second set of abrasive particles are also precisionshaped abrasive particles, in one embodiment. The second set of abrasiveparticles may be triangular prisms, as indicated in block 432, rodshaped, as indicated in block 434, another polygonal shaped prism, asindicated in block 436, or another suitable shape, as indicated in block438. The second set of abrasive particles may be deposited and orientedon the backing using any suitable method, such as using electrostaticalignment, as indicated in block 432, or using magnetic alignment, asindicated in block 434, or oriented and placed using an alignment tool,as illustrated in block 446. Additionally, the second set of abrasiveparticles may be placed with some randomness, as indicated in block 448,such that an average density of second abrasive particles are present,but alignment is not precise. Other alignment and orientation methodsare also expressly contemplated, as indicated in block 449.

First and second particle sets may be the same shape, for exampletriangles 412 and triangles 432, or may be different shapes, such astriangles 412 and rods 434, for example. Other shapes and combinationsare also expressly contemplated.

First and second particle sets may be the same size, in one embodiment.In another embodiment, first and second particle sets are differentsizes. For example, the second particle set may include smallerparticles that more easily fit between placed particles of the firstparticle set.

Additionally, while FIG. 5 illustrates placement of a first and secondset of particles, it is expressly contemplated that a third set ofparticles may also be present and used to create a closed coat (i.e.,substantially the maximum possible number of abrasive particles ofnominal specified grade(s) that can be retained in the abrasive layer).In some embodiments the third particle set includes crushed particles.The third particle set may include crushed particles that are smallerthan the first and / or second particle sets. The third particle set maybe randomly deposited to fill in gaps between the first and second setsof particles.

The first and second sets of abrasive particles may be embedded withinthe make coat and aligned using the same, or different depositionmethods. For example, since the first abrasive particles are orientedand aligned with the intention of performing an abrading operation, theymay be precisely aligned, for example using an alignment tool or usingmagnetic alignment methods. The second set of abrasive particles may beplaced, in some embodiments, using a less precise method, such aselectrostatic alignment or drop coating. In other embodiments, the firstand second sets of abrasive particles are oriented using the samemethod. For example, an alignment tool may allow for simultaneousplacement of the first and second sets of abrasive particles.Alternatively, each of a first and second tool, with different cavityarrangements can be used to place the particles.

Examples of suitable abrasive particles for first and / or second setsof abrasive particles include: fused aluminum oxide; heat-treatedaluminum oxide; white fused aluminum oxide; ceramic aluminum oxidematerials such as those commercially available under the tradedesignation 3M CERAMIC ABRASIVE GRAIN from 3M Company, St. Paul, MN;brown aluminum oxide; blue aluminum oxide; silicon carbide (includinggreen silicon carbide); titanium diboride; boron carbide; tungstencarbide; garnet; titanium carbide; diamond; cubic boron nitride; garnet;fused alumina zirconia; iron oxide; chromia; zirconia; titania; tinoxide; quartz; feldspar; flint; emery; sol-gel-derived abrasiveparticles; and combinations thereof. Of these, molded sol-gel derivedalpha alumina abrasive particles are preferred in many embodiments.Abrasive material that cannot be processed by a sol-gel route may bemolded with a temporary or permanent binder to form shaped precursorparticles which are then sintered to form shaped abrasive particles, forexample, as described in U. S. Pat. Appln. Publ. No. 2016/0068729 A1(Erickson et al.).

Examples of sol-gel-derived abrasive particles and methods for theirpreparation can be found in U. S. Pat. Nos. 4,314,827 (Leitheiser etal.); 4,623,364 (Cottringer et al.); 4,744,802 (Schwabel), 4,770,671(Monroe et al.); and 4,881,951 (Monroe et al.). It is also contemplatedthat the abrasive particles could include abrasive agglomerates such,for example, as those described in U. S. Pat. Nos. 4,652,275 (Bloecheret al.) or 4,799,939 (Bloecher et al.). In some embodiments, first and /or abrasive particles may be surface-treated with a coupling agent(e.g., an organosilane coupling agent) or other physical treatment(e.g., iron oxide or titanium oxide) to enhance adhesion of the abrasiveparticles to the binder (e.g., make and/or size layer). The abrasiveparticles may be treated before combining them with the correspondingbinder precursor, or they may be surface treated in situ by including acoupling agent to the binder.

Preferably, first and / or second abrasive particles are ceramicabrasive particles such as, for example, sol-gel-derived polycrystallinealpha alumina particles. Abrasive particles composed of crystallites ofalpha alumina, magnesium alumina spinel, and a rare earth hexagonalaluminate may be prepared using sol-gel precursor alpha aluminaparticles according to methods described in, for example, U. S. Pat. No.5,213,591 (Celikkaya et al.) and U. S. Pat. Appln. Publ. Nos.2009/0165394 A1 (Culler et al.) and 2009/0169816 A1 (Erickson et al.).

Alpha alumina-based triangular abrasive particles can be made accordingto well-known multistep processes. Briefly, the method includes thesteps of making either a seeded or non-seeded sol-gel alpha aluminaprecursor dispersion that can be converted into alpha alumina; fillingone or more mold cavities having the desired outer shape of the abrasiveparticle with the sol-gel, drying the sol-gel to form precursortriangular abrasive particles; removing the precursor abrasive particlesfrom the mold cavities; calcining the precursor abrasive particles toform calcined, precursor abrasive particles, and then sintering thecalcined, precursor abrasive particles to form the first and / or secondset of abrasive particles. The process will now be described in greaterdetail.

Further details concerning methods of making sol-gel-derived abrasiveparticles can be found in, for example, U. S. Pat. Nos. 4,314,827(Leitheiser); 5,152,917 (Pieper et al.); 5,435,816 (Spurgeon et al.);5,672,097 (Hoopman et al.); 5,946,991 (Hoopman et al.); 5,975,987(Hoopman et al.); and 6,129,540 (Hoopman et al.); and in U. S. Publ.Pat. Appln. No. 2009/0165394 A1 (Culler et al.).

Examples of slurry derived alpha alumina abrasive particles can be foundin WO 2014/070468, published on May 8, 2014. Slurry derived particlesmay be formed from a powder precursor, such as alumina oxide powder. Theslurry process may be advantageous for larger particles that can bedifficult to make using sol-gel techniques.

The abrasive particles may undergo a sintering process, such as theprocess described in U.S. Pat. 10400146, issued on Sep. 3, 2019, forexample. However, other processing techniques are expresslycontemplated.

Ultra-fine grain shaped grains may be formed using techniques describedin U.S. PAP 2019/0233693, published on Aug. 1, 2019, or in WO2018023177, published on Dec. 20, 2018, or in WO 2018/207145, publishedon Nov. 15, 2018.

Softer shaped grain particles, with Mohs hardness’ between 2.0 and 5.0,that can be used for non-scratch applications, can be made according tomethods described in WO 2019/215539, published on Nov. 14, 2019.

In some preferred embodiments, the abrasive particles areprecisely-shaped in that individual abrasive particles will have a shapethat is essentially the shape of the portion of the cavity of a mold orproduction tool in which the particle precursor was dried, prior tooptional calcining and sintering.

Abrasive particles used in the present disclosure can typically be madeusing tools (i.e., molds) cut using precision machining, which provideshigher feature definition than other fabrication alternatives such as,for example, stamping or punching.

The shaped abrasive particles can have at least one sidewall, which maybe a sloping sidewall. In some embodiments, more than one (for exampletwo or three) sloping sidewall can be present and the slope or angle foreach sloping sidewall may be the same or different. In otherembodiments, the sidewall can be minimized for particles where the firstand the second faces taper to a thin edge or point where they meetinstead of having a sidewall. The sloping sidewall can also be definedby a radius, R (as illustrated in FIG. 5B of US Patent Application No.2010/0151196). The radius, R, can be varied for each of the sidewalls.

Specific examples of shaped particles having a ridge line includeroof-shaped particles, for example particles as illustrated, in FIGS. 4Ato 4C of WO 2011/068714. Preferred, roof-shaped particles includeparticles having the shape of a hip roof, or hipped roof (a type of roofwherein any sidewalls facets present slope downwards from the ridge lineto the first side. A hipped roof typically does not include verticalsidewall(s) or facet(s)).

Methods for making shaped abrasive particles having at least one slopingsidewall are for example described in US Pat. Application PublicationNo. 2009/0165394.

Shaped abrasive particles can also include a plurality of ridges ontheir surfaces. The plurality of grooves (or ridges) can be formed by aplurality of ridges (or grooves) in the bottom surface of a mold cavitythat have been found to make it easier to remove the precursor shapedabrasive particles from the mold.

The plurality of grooves (or ridges) is not particularly limited andcan, for example, include parallel lines which may or may not extendcompletely across the side. Preferably, the parallel lines intersectwith the perimeter along a first edge at a 90° angle. Thecross-sectional geometry of a groove or ridge can be a truncatedtriangle, triangle, or other geometry as further discussed in thefollowing. In various embodiments of the invention, the depth, of theplurality of grooves can be between about 1 micrometer to about 400micrometers.

According to another embodiment the plurality of grooves include a crosshatch pattern of intersecting parallel lines which may or may not extendcompletely across the face. In various embodiments, the cross hatchpattern can use intersecting parallel or non-parallel lines, variouspercent spacing between the lines, arcuate intersecting lines, orvarious cross-sectional geometries of the grooves. In other embodimentsthe number of ridges (or grooves) in the bottom surface of each moldcavity can be between 1 and about 100, or between 2 to about 50, orbetween about 4 to about 25 and thus form a corresponding number ofgrooves (or ridges) in the shaped abrasive particles.

Methods for making shaped abrasive particles having grooves on at leastone side are for example described in US Pat. Application PublicationNo. 2010/0146867.

The shaped abrasive particles may also have one or more notches on oneof the faces of the abrasive particle, as described in PCT ApplicationSer. No. IB2019/060861, filed on Dec. 16, 2019.

Shaped abrasive particles can have an opening (preferably one extendingor passing through the first and second side). Methods for making shapedabrasive particles having an opening are for example described in USPat. Application Publication No. 2010/0151201 and 2009/0165394.

Shaped abrasive particles can also have at least one recessed (orconcave) face or facet; at least one face or facet which is shapedoutwardly (or convex). Methods for making dish-shaped abrasive particlesare for example described in US Pat. Application Publication Nos.2010/0151195 and 2009/0165394. Additionally, shaped abrasive particlesmay also have a multifaceted surface as described in U.S. Pat.10,150,900, issued on Dec. 11, 2018.

Shaped abrasive particles can also have at least one fractured surface.Methods for making shaped abrasive particles with at least one fracturedsurface are for example described in US Pat. Application PublicationNos. 2009/0169816 and 2009/0165394.

Shaped abrasive particles can also have a cavity. Shaped abrasiveparticles may also include an aperture, such as that described in U.S.Pat. 8,142,532, issued on Mar. 27, 2012, herein incorporated byreference.

Shaped abrasive particles can also have a low roundness factor. Methodsfor making shaped abrasive particles with low Roundness Factor are forexample described in US Pat. Application Publication No. 2010/0319269.

Shaped abrasive particles may have a second vertex on a second side, asdescribed in U.S. 9,447,311, issued on Sep. 16, 2016. Methods for makingabrasive particles wherein the second side is a vertex (for example,dual tapered abrasive particles) or a ridge line (for example, roofshaped particles) are for example described in U.S. PAP 2012/022733,published on Sep. 13, 2012.

Shaped abrasive particles may be formed to have sharp tips, such asthose described in U.S. PAP 2019/0233693, published on Aug. 1, 2019, orin U.S. Provisional Application with Serial No. 62/877443, filed on Jul.23, 2019.

Shaped abrasive particles may also be formed to include a rake angle,such as those described in WO 2019/207423, published on Oct. 31, 2019,or in WO 2019/207417, published on Oct. 31, 2019, or in PCT ApplicationSer. No. IB 2019/059112, filed on Oct. 24, 2019.

Shaped abrasive particles may also be formed to have a precision shapedportion and a non-shaped portion, such as a crushed portion, asdescribed in U.S. Provisional Pat. Application 62/833865, filed on Apr.15, 2019.

Shaped abrasive particles can also have a combination of one or more ofshape features discussed herein, including a sloping sidewall, a groove,a recess, a facet, a fractured surface, a cavity, more than one vertex,sharp edges, a non-shaped portion, a notch, a rake angle and / or a lowroundness factor.

As used herein in referring to triangular abrasive particles, the term“length” refers to the maximum dimension of a triangular abrasiveparticle. “Width” refers to the maximum dimension of the triangularabrasive particle that is perpendicular to the length. The terms“thickness” or “height” refer to the dimension of the triangularabrasive particle that is perpendicular to the length and width. Forabrasive particles with shapes other than triangles, length refers to alongest dimension, and width refers to the maximum dimensionperpendicular to the length, while thickness refers to a dimensionperpendicular to both the length and width.

The shaped abrasive particles may have an elongated shape, such as thatdescribed in U.S. PAP 2019/0106362, published on Apr. 11, 2019, or in WO2019/069157, published on Apr. 11, 2019. The elongate shape may betriangular-prism shaped, rod-shaped, or otherwise including one or morevertices along the perimeter.

The shaped abrasive particles may have a variable cross-sectional areaalong a length of the particle, such as those described in U. S. PAP2019/0249051. For example, the shaped abrasive particles may be dogboneshaped, or otherwise have a cross sectional area that varies from afirst end to a second end.

The shaped abrasive particles may have a tetrahedron shape, such asthose described in WO 2018/207145, published on Nov. 15, 2018, or thoseof U.S. Pat. No. 9,573,250, issued on Feb. 21, 2017.

The shaped abrasive particles may also have a concave or convex portion,or may be defined as having one or more acute interior angles, such asthose described in U.S. 10,301,518, issued on May 28, 2019.

The shaped abrasive particles may also include shape-on-shape particles,such as a plate on plate shaped particle as described in 8,728,185,issued on May 20, 2014.

The shaped abrasive particles may also include shaped abrasive particlesthat have an irregular polygonal shape, as described in U.S. ProvisionalPat. Application 62/924956, filed on Oct. 23, 2019.

The shaped abrasive particles may also be shaped to be self-standingabrasive particles, such that cutting portions are more likely to embedin a make coat, for example, in an orientation away from the backing,such as those described in PCT Application with Ser. No. IB 2019/060457,filed on Dec. 4, 2019.

The first and / or second sets of abrasive particles are typicallyselected to have a length in a range of from 1 micron to 15000 microns,more typically 10 microns to about 10000 microns, and still moretypically from 150 to 2600 microns, although other lengths may also beused.

The first set of abrasive particles are typically selected to have awidth in a range of from 0.1 micron to 3500 microns, more typically 100microns to 3000 microns, and more typically 100 microns to 2600 microns,although other lengths may also be used.

Abrasive particles are typically selected to have a thickness in a rangeof from 0.1 micron to 1600 microns, more typically from 1 micron to 1200microns, although other thicknesses may be used. In some embodiments,Abrasive particles may have an aspect ratio (length to thickness) of atleast 2, 3, 4, 5, 6, or more.

Surface coatings either of the first and / or second abrasive particlesmay be used to improve the adhesion between abrasive particles and abinder in abrasive articles, or can be used to aid in electrostaticdeposition of the abrasive particles. In one embodiment, surfacecoatings as described in U. S. Pat. No. 5,352,254 (Celikkaya) in anamount of 0.1 to 2 percent surface coating to abrasive particle weightmay be used. Such surface coatings are described in U. S. Pat. Nos.5,213,591 (Celikkaya et al.); 5,011,508 (Wald et al.); 1,910,444(Nicholson); 3,041,156 (Rowse et al.); 5,009,675 (Kunz et al.);5,085,671 (Martin et al.); 4,997,461 (Markhoff-Matheny et al.); and5,042,991 (Kunz et al.). Additionally, the surface coating may preventthe abrasive particle from capping. Capping is the term to describe thephenomenon where metal particles from the workpiece being abraded becomewelded to the tops of the abrasive particles. Surface coatings toperform the above functions are known to those of skill in the art.

The abrasive particles may be independently sized according to anabrasives industry recognized specified nominal grade. Exemplaryabrasive industry recognized grading standards include those promulgatedby ANSI (American National Standards Institute), FEPA (Federation ofEuropean Producers of Abrasives), and JIS (Japanese IndustrialStandard). ANSI grade designations (i.e., specified nominal grades)include, for example: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 36,ANSI 46, ANSI 54, ANSI 60, ANSI 70, ANSI 80, ANSI 90, ANSI 100, ANSI120, ANSI 150, ANSI 180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI360, ANSI 400, and ANSI 600. FEPA grade designations include F4, F5, F6,F7, F8, F10, F12, F14, F16, F20, F22, F24, F30, F36, F40, F46, F54, F60,F70, F80, F90, F100, F120, F150, F180, F220, F230, F240, F280, F320,F360, F400, F500, F600, F800, F1000, F1200, F1500, and F2000. JIS gradedesignations include JIS8, JIS12, JIS16, JIS24, JIS36, JIS46, JIS54,JIS60, JIS80, JIS100, JIS150, JIS180, JIS220, JIS240, JIS280, JIS320,JIS360, JIS400, JIS600, JIS800, JIS1000, JIS1500, JIS2500, JIS4000,JIS6000, JIS8000, and JIS10000. According to one embodiment of thepresent disclosure, the average diameter of the abrasive particles maybe within a range of from 260 to 1400 microns in accordance with FEPAgrades F60 to F24.

Alternatively, the abrasive particles can be graded to a nominalscreened grade using U. S.A. Standard Test Sieves conforming to ASTME-11 “Standard Specification for Wire Cloth and Sieves for TestingPurposes”. ASTM E-11 prescribes the requirements for the design andconstruction of testing sieves using a medium of woven wire clothmounted in a frame for the classification of materials according to adesignated particle size. A typical designation may be represented as-18+20 meaning that the abrasive particles pass through a test sievemeeting ASTM E-11 specifications for the number 18 sieve and areretained on a test sieve meeting ASTM E-11 specifications for the number20 sieve. In one embodiment, the abrasive particles have a particle sizesuch that most of the particles pass through an 18 mesh test sieve andcan be retained on a 20, 25, 30, 35, 40, 45, or 50 mesh test sieve. Invarious embodiments, the abrasive particles can have a nominal screenedgrade of: -18+20, -20+25, -25+30, -30+35, -35+40, -40+45, -45+50,-50+60, -60+70, -70+80, -80+100, -100+120, -120+140, -140+170, -170+200,-200+230, -230+270, -270+325, -325+400, -400+450, -450+500, or -500+635.Alternatively, a custom mesh size can be used such as -90+100.

Once the first and second abrasive particles have been embedded in themake layer precursor, it is at least partially cured in order topreserve orientation of the mineral during application of the size layerprecursor. Typically, this involves B-staging the make layer precursor,but more advanced cures may also be used if desired. B-staging may beaccomplished, for example, using heat and/or light and/or use of acurative, depending on the nature of the make layer precursor selected.

In block 450, a size coat is applied over the embedded particles. Thesize layer precursor is applied over the at least partially cured makelayer precursor and triangular abrasive particles. The size layer can beformed by coating a curable size layer precursor onto a major surface ofthe backing. The size layer precursor may include for example, glue,phenolic resin, aminoplast resin, urea-formaldehyde resin,melamine-formaldehyde resin, urethane resin, free-radicallypolymerizable polyfunctional (meth)acrylate (e.g., aminoplast resinhaving pendant a,β-unsaturated groups, acrylated urethane, acrylatedepoxy, acrylated isocyanurate), epoxy resin (including bis-maleimide andfluorene-modified epoxy resins), isocyanurate resin, and mixturesthereof. If phenolic resin is used to form the make layer, it islikewise preferably used to form the size layer. The size layerprecursor may be applied by any known coating method for applying a sizelayer to a backing, including roll coating, extrusion die coating,curtain coating, knife coating, gravure coating, spray coating, and thelike. If desired, a presize layer precursor or make layer precursoraccording to the present disclosure may be also used as the size layerprecursor.

The basis weight of the size layer will also necessarily vary dependingon the intended use(s), type(s) of abrasive particles, and nature of thecoated abrasive belt being prepared, but generally will be in the rangeof from 1 or 5 gsm to 300, 400, or even 500 gsm, or more. The size layerprecursor may be applied by any known coating method for applying a sizelayer precursor (e.g., a size coat) to a backing including, for example,roll coating, extrusion die coating, curtain coating, and spray coating.

Once applied, the size layer precursor, and typically the partiallycured make layer precursor, are sufficiently cured to provide a usablecoated abrasive article. In general, this curing step involves thermalenergy, although other forms of energy such as, for example, radiationcuring may also be used. Useful forms of thermal energy include, forexample, heat and infrared radiation. Exemplary sources of thermalenergy include ovens (e.g., festoon ovens), heated rolls, hot airblowers, infrared lamps, and combinations thereof.

In addition to other components, binder precursors, if present, in themake layer precursor and/or presize layer precursor of coated abrasivebelts according to the present disclosure may optionally containcatalysts (e.g., thermally activated catalysts or photocatalysts),free-radical initiators (e.g., thermal initiators or photoinitiators),curing agents to facilitate cure. Such catalysts (e.g., thermallyactivated catalysts or photocatalysts), free-radical initiators (e.g.,thermal initiators or photoinitiators), and/or curing agents may be ofany type known for use in coated abrasive belts including, for example,those described herein.

In addition to other components, the make and size layer precursors mayfurther contain optional additives, for example, to modify performanceand/or appearance. Exemplary additives include grinding aids, fillers,plasticizers, wetting agents, surfactants, pigments, coupling agents,fibers, lubricants, thixotropic materials, antistatic agents, suspendingagents, and/or dyes.

Exemplary grinding aids, which may be organic or inorganic, includewaxes, halogenated organic compounds such as chlorinated waxes liketetrachloronaphthalene, pentachloronaphthalene, and polyvinyl chloride;halide salts such as sodium chloride, potassium cryolite, sodiumcryolite, ammonium cryolite, potassium tetrafluoroborate, sodiumtetrafluoroborate, silicon fluorides, potassium chloride, magnesiumchloride; and metals and their alloys such as tin, lead, bismuth,cobalt, antimony, cadmium, iron, and titanium. Examples of othergrinding aids include sulfur, organic sulfur compounds, graphite, andmetallic sulfides. A combination of different grinding aids can be used.

Exemplary antistatic agents include electrically conductive materialsuch as vanadium pentoxide (e.g., dispersed in a sulfonated polyester),humectants, carbon black and/or graphite in a binder.

Examples of useful fillers for this disclosure include silica such asquartz, glass beads, glass bubbles and glass fibers; silicates such astalc, clays, (montmorillonite) feldspar, mica, calcium silicate, calciummetasilicate, sodium aluminosilicate, sodium silicate; metal sulfatessuch as calcium sulfate, barium sulfate, sodium sulfate, aluminum sodiumsulfate, aluminum sulfate; gypsum; vermiculite; wood flour; aluminumtrihydrate; carbon black; aluminum oxide; titanium dioxide; cryolite;chiolite; and metal sulfites such as calcium sulfite.

Additionally, in some embodiments, in block 460, a supersize coat isapplied over the size coat. The supersize coat may include fillers,grinding aids, lubricants, or suitable other materials.

Optionally a supersize layer may be applied to at least a portion of thesize layer. If present, the supersize typically includes grinding aidsand/or anti-loading materials. The optional supersize layer may serve toprevent or reduce the accumulation of swarf (the material abraded from aworkpiece) between abrasive particles, which can dramatically reduce thecutting ability of the coated abrasive belt. Useful supersize layerstypically include a grinding aid (e.g., potassium tetrafluoroborate),metal salts of fatty acids (e.g., zinc stearate or calcium stearate),salts of phosphate esters (e.g., potassium behenyl phosphate), phosphateesters, urea-formaldehyde resins, mineral oils, crosslinked silanes,crosslinked silicones, and/or fluorochemicals. Useful supersizematerials are further described, for example, in U. S. Pat. No.5,556,437 (Lee et al.). Typically, the amount of grinding aidincorporated into coated abrasive products is about 50 to about 400 gsm,more typically about 80 to about 300 gsm. The supersize may contain abinder such as for example, those used to prepare the size or makelayer, but it need not have any binder.

Further details concerning the construction of coated abrasive articlescomprising an abrasive layer secured to a backing, wherein the abrasivelayer includes abrasive particles and make, size, and optional supersizelayers are well known, and may be found, for example, in U. S. Pat. Nos.4,734,104 (Broberg); 4,737,163 (Larkey); 5,203,884 (Buchanan et al.);5,152,917 (Pieper et al.); 5,378,251 (Culler et al.); 5,417,726 (Stoutet al.); 5,436,063 (Follett et al.); 5,496,386 (Broberg et al.);5,609,706 (Benedict et al.); 5,520,711 (Helmin); 5,954,844 (Law et al.);5,961,674 (Gagliardi et al.); 4,751,138 (Bange et al.); 5,766,277 (DeVoeet al.); 6,077,601 (DeVoe et al.); 6,228,133 (Thurber et al.); and No.5,975,988 (Christianson).

FIG. 6 is a schematic cross-sectional view of an abrasive articledeposition process for a coated abrasive article. An abrasive article500 includes a backing 510 to which a make coat precursor 520 has beenapplied. A first set of abrasive particles 530 are embedded in make coat520 such that a long base edge 534 is coupled to backing 510 and a tip532 faces away from the backing. However, while triangles areillustrated in FIG. 6 , other shapes are also expressly contemplated.For example, tetrahedrons could also be placed with a bottom facecoupled to backing 510 and a tip facing away from backing 510. Othershaped abrasive grains can also be suitably deposited onto backing 510.

A second set of abrasive grains 540 are illustrated in FIG. 6 during adeposition phase. However, while abrasive grains 540 are illustrated intheir post orientation and alignment positions, it is expresslycontemplated that, in some embodiments, at least some alignment occursafter particles 540 are placed. Particles 540 are illustrated as havingan opposite orientation to particles 530, with a long edge 542 facingaway from backing 510 and a tip 544 facing backing 510. From an abradingstandpoint, the presence of long edge 542 facing away from backing 510is generally not desired because edge 542 of particle 540 generally doesnot offer as much abrading efficacy as tip 544.

Surprisingly, it was found, as discussed in greater detail in theExamples herein, that having a portion of abrasive particle in the 540orientation resulted in better overall wear performance of an abrasivearticle. As illustrated by the ratio 550, in some embodiments a majorityof abrasive particles are present in a primary orientation 530. In someembodiments, the percentage of abrasive particles present in orientation540 is as low as 1%. The percentage of abrasive particles in secondorientation may be higher, in some embodiments, for example, 2%, 3%, 4%,5%, 8%, 10%, 15%, or even 20%, as illustrated in FIG. 6 . However, asdescribed in the Examples in greater detail, increasing the percentageof particles in the secondary orientation higher does result in adecrease in abrading efficacy of abrasive article 500.

FIG. 7 is a top down schematic of a coated abrasive article accordancewith embodiments described herein. While FIG. 6 illustrates anembodiment where a second set of abrasive particles are precisely shapedwith respect to the first set of abrasive particles, FIG. 7 illustratesan article 700 with row of abrasive particles on a backing 710. Withinthe rows are two types of abrasive particles, a primary set of abrasiveparticles 720, which are in an abrading orientation and a secondary setof abrasive particles 730 are present in a secondary orientation. Thesecond orientation may be opposite the abrading orientation, asillustrated in FIG. 6 , in some embodiments. However, in otherembodiments, the secondary orientation may include secondary abrasiveparticles oriented at an angle with respect to primary abrasiveparticles.

FIGS. 8A and 8B illustrated close up views of coated abrasive articles.As illustrated in FIG. 8A, a coated abrasive particle 800, prior to sizeand supersize coating application, includes rows 812 of abrasiveparticles 810 with spacings 814 in between adjacent particles. Rows 812have spacings 816 in between. As illustrated in FIG. 8A, a second set ofparticles 820 has been deposited such that particles 820 generally havea different orientation with respect to particles 810. Many particles820 have landed in spacings 816 between rows 812 of particles 810 with along edge facing away from the backing. Particles 820 may have an anglewith respect to a backing (e.g. not standing perpendicular to backing),may be at an angle with respect to particles 810 (e.g. having a facethat is not parallel to particles 810 in rows 812). While some particles820, as illustrated in FIG. 8B, may have an orientation with a facesubstantially parallel to the backing, the majority of particles 820 areoriented such that a tip generally faces the backing and an edgegenerally faces away from the backing. A third set of particles 830 mayalso be present to create a closed coat. As illustrated in FIGS. 8A and8B, the third set of particles 830 includes crushed particles of asmaller grade than either first or second particles 810, 820,respectively.

Examples of workpiece materials include metal, metal alloys, steel,steel alloys, aluminum, exotic metal alloys, ceramics, glass, wood,wood-like materials, composites, painted surfaces, plastics, reinforcedplastics, stone, and/or combinations thereof. The workpiece may be flator have a shape or contour associated with it. Exemplary workpiecesinclude metal components, plastic components, particleboard, camshafts,crankshafts, furniture, and turbine blades.

An abrasive article is presented. The abrasive article includes a firstset of shaped abrasive particles. A majority of the first set of shapedabrasive particles are oriented with respect to a backing in a firstorientation. The abrasive article includes a second set of shapedabrasive particles. A majority of the second set of shaped abrasiveparticles are oriented with respect to the backing in a secondorientation. The second orientation differs from the first orientation.The first and second set of shaped abrasive particles are embeddedwithin a make coat layer on the backing.

The article may be implemented such that each of the first set of shapedabrasive particles includes a base portion and an abrading portion. Thebase portion is embedded within the make coat layer and the abradingportion faces away from the backing.

The article may be implemented such that some of the second set ofshaped abrasive particles are oriented at least 90° with respect to themajority of the first set of shaped abrasive particles.

The article may be implemented such that the majority of the second setof shaped abrasive particles are oriented up to 180° with respect to themajority of the first set of shaped abrasive particles.

The article may be implemented such that it further includes a third setof abrasive particles forming a closed coat on the backing.

The article may be implemented such that the first set of shapedabrasive particles are oriented with respect to each other, such thatfaces of adjacent abrasive particles are parallel.

The article may be implemented such that the first set of shapedabrasive particles are more than 60% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 0.5% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 1% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 2% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 5% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 10% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 15% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are at least 20% by weight of the first and secondsets of shaped abrasive particles.

The article may be implemented such that the second set of shapedabrasive particles are 25% by weight or less of the first and secondsets of shaped abrasive particles.

The article may be implemented such that one of the first and secondsets of abrasive particles are magnetically responsive.

The article may be implemented such that the abrasive article is anabrasive belt or an abrasive disc.

The article may be implemented such that the first set of shapedabrasive particles are rods, tetrahedrons, right angle triangularprisms, isosceles triangular prisms, equilateral triangular prisms,scalene triangular prisms, trapezoidal prisms, crescents, stars, cubes,dual tapered, or shape-on-shape.

The article may be implemented such that the second set of shapedabrasive particles are rods, tetrahedrons, right angle triangularprisms, isosceles triangular prisms, equilateral triangular prisms,scalene triangular prisms, trapezoidal prisms, crescents, stars, cubes,dual-tapered, shape-on-shape, or agglomerates.

The article may be implemented such that first set of shaped abrasiveparticles and the second set of shaped abrasive particles are the sameshape.

The article may be implemented such that the first set of shapedabrasive particles and the second set of shaped abrasive particles aredifferent shapes.

The article may be implemented such that the first set of shapedabrasive particles and the second set of shaped abrasive particles aresubstantially the same size.

The article may be implemented such that the first set of shapedabrasive particles and the second set of shaped abrasive particles aredifferent sizes.

The article may be implemented such that the coating layer is a makecoat layer.

The article may be implemented such that the coating layer is a sizecoat.

The article may be implemented such that the coating layer is asupersize coat.

The article may be implemented such that the backing is a woven ornonwoven article.

The article may be implemented such that the second set of particles arewithin 10% of an average tip height for the first set of particles.

The article may be implemented such that the second set of particles arewithin 15% of an average tip height for the first set of particles.

The article may be implemented such that the second set of particles arewithin 20% of an average tip height for the first set of particles.

The article may be implemented such that the second set of particles arewithin 25% of an average tip height for the first set of particles.

A method of making a coated abrasive article is presented. The methodincludes coating a backing with a coating precursor layer. The methodalso includes embedding a first set of abrasive particles within themake coat precursor. A majority of the first set of abrasive particleshave a first orientation with respect to the backing and are orientedsuch that faces of adjacent particles are parallel to each other. Themethod also includes embedding a second set of abrasive particles withinthe coating precursor layer. A majority of the second set of abrasiveparticles have a second orientation with respect to the backing. Themethod also includes curing the coating precursor layer.

The method may be implemented such that the coating precursor layer is amake coat. The method may also include applying a size coat over atleast one of the first and second sets of abrasive particles.

The method may be implemented such that the coating precursor layer is asize coat. The method also includes applying a make coat to the backing.

The method may be implemented such that the first set of abrasiveparticles are embedded within the make coat. The second set of abrasiveparticles are embedded within the size coat.

The method may be implemented such that the coating precursor layer is asupersize coat. The method may also include applying a make coat and asize coat to the backing.

The method may be implemented such that the coated abrasive article isan abrasive disc or an abrasive belt.

The method may also include embedding a third set of abrasive particleswithin the make coat precursor.

The method may be implemented such that the third set of abrasiveparticles are smaller than the first or second set of abrasiveparticles.

The method may be implemented such that the third set of abrasiveparticles are crushed abrasive particles.

The method may also include filling an alignment tool with the first setof abrasive particles such that a plurality of cavities within thealignment tool receive one of the first set of abrasive particles, andpositioning the alignment tool such that each of the first set ofabrasive particles move out of the plurality of cavities and embedwithin the make coat.

The method may be implemented such that the first set of abrasiveparticles are magnetically responsive. Embedding the first set ofabrasive particles within the make coat precursor may include exposingthe first set of abrasive particles to a magnetic field such that thefirst set of abrasive particles move into the first orientation.

The method may be implemented such that the second set of abrasiveparticles are magnetically responsive. Embedding the second set ofabrasive particles within the make coat precursor may include exposingthe second set of abrasive particles to a magnetic field such that thesecond set of abrasive particles move into the first orientation.

The method may be implemented such that embedding the second set ofabrasive particles within the make coat precursor includes exposing thesecond set of abrasive particles to an electrostatic field such that thesecond set of abrasive particles move into the second orientation.

The method may be implemented such that embedding the second set ofabrasive particles within the make coat precursor includes drop coatingthe second set of abrasive particles. The first orientation may includethe first set of abrasive particles aligned in rows on the backing. Thesecond orientation may include each of the second set of abrasiveparticles embedding into the make coat in a space between a first rowand a second row of the first set of abrasive particles.

The method may be implemented such that the first set of abrasiveparticles are shaped as one of: triangular prisms, rods, tetrahedrons,crescents, stars, cubes, rectangular prisms, or another regularpolygonal prism.

The method may be implemented such that the second set of abrasiveparticles are shaped as one of: triangular prisms, rods, tetrahedrons,crescents, stars, cubes, rectangular prisms, or another regularpolygonal prism.

The method may be implemented such that the first and second sets ofabrasive particles are the same shape.

The method may be implemented such that the first and second sets ofabrasive particles are different shapes.

The method may be implemented such that the first set of abrasiveparticles include a first size, the second set of abrasive particlesinclude a second size. The first and second sizes are the same.

The method may be implemented such that the first set of abrasiveparticles are a first size, the second set of abrasive particles are asecond size, and the first and second sizes are different.

An abrasive article is presented that includes a backing and a coatinglayer applied to the backing. The abrasive article includes a first setof shaped abrasive particles, each of the first set of shaped abrasiveparticles having a first base edge and a first cutting portion. Thefirst set of shaped abrasive particles are in a first orientation withthe first base edge embedded within the coating layer and the firstcutting portion oriented away from the backing. The abrasive articleincludes a second set of shaped abrasive particles, each of the secondset of shaped abrasive particles having a second base edge and a secondcutting portion. The second set of shaped abrasive particles are in asecond orientation with the second cutting portion embedded within thecoating layer and the first base edge facing away from the backing.

The abrasive article may be implemented such that the first orientationincludes the first set of abrasive particles aligned such that faces ofadjacent particles are substantially parallel.

The abrasive article may be implemented such that the first set ofshaped abrasive particles and the second set of shaped abrasiveparticles are the same shape.

The abrasive article may be implemented such that the first set ofshaped abrasive particles and the second set of shaped abrasiveparticles are different shapes.

The abrasive article may be implemented such that the first set ofshaped abrasive particles and the second set of shaped abrasiveparticles are substantially the same size.

The abrasive article may be implemented such that the first set ofshaped abrasive particles and the second set of shaped abrasiveparticles are different sizes.

The abrasive article may be implemented such that it includes a thirdset of abrasive particles that are smaller than the first set of shapedabrasive particles.

The abrasive article may be implemented such that the third set ofabrasive particles are crushed abrasive particles.

The abrasive article may be implemented such that the cutting portionincludes a cutting tip or a cutting edge.

The abrasive article may be implemented such that the first set ofshaped abrasive particles are more than 60% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 0.5% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 1% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 2% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 5% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 10% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 15% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are at least 20% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are 25% by weight or less of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that one of the first andsecond sets of abrasive particles are magnetically responsive.

The abrasive article may be implemented such that the abrasive articleis an abrasive belt or an abrasive disc.

The abrasive article may be implemented such that the coating layer is amake coat layer.

The abrasive article may be implemented such that the coating layerincludes a make coat layer and a size coat layer and the first set ofshaped abrasive particles are embedded within the make coat layer.

The abrasive article may be implemented such that the second set ofshaped abrasive particles are embedded within the size coat layer.

An abrasive article is presented that includes a backing and a make coatlayer adhered to the backing. The abrasive article also includes a firstset of abrasive particles embedded within the make coat layer. Each ofthe first set of abrasive particles has a first axis of rotationextending from a first base, and each of the first set of abrasiveparticles are orientated such that the first base is embedded within themake coat layer. The abrasive article also includes a second coat layerapplied over the embedded first set of abrasive particles. The abrasivearticle also includes a second set of abrasive particles embedded withinthe make coat layer or second coat layer. Each of the second set ofabrasive particles has a second axis of rotation extending from a secondbase. Each of the second set of abrasive particles are oriented suchthat the second base faces away from the backing.

The abrasive article may be implemented such that the first set ofabrasive particles has a cutting edge, and the axis of rotation isdefined by a line extending through the cutting edge and the base.

The abrasive article may be implemented such that each of the first setof abrasive particles are aligned such that adjacent bases aresubstantially parallel.

The abrasive article may be implemented such that each of the first setof abrasive particles are aligned such that adjacent axes of rotationsare parallel.

The abrasive article may be implemented such that second bases ofadjacent particles at oriented at an angle with respect to each other.

The abrasive article may be implemented such that the first set ofabrasive particles are arranged in rows on the backing with a particlespacing between adjacent particles and a row spacing between adjacentrows.

The abrasive article may be implemented such that the second set ofabrasive particles are embedded within the make coat layer or size coatlayer such that a majority are embedded in the row spacings.

The abrasive article may be implemented such that it includes a thirdset of abrasive particles forming a closed coat.

The abrasive article may be implemented such that the coat layer is asize coat.

The abrasive article may be implemented such that it also includes asupersize coat.

The abrasive article may be implemented such that the coat layer is thesupersize coat.

The abrasive article may be implemented such that the first and secondsets of abrasive particles are shaped abrasive particles. The shape ofeach of the first and second sets of abrasive articles are selected fromthe group consisting of: triangular prisms, trapezoidal prisms,tetrahedrons, crescents, stars, rectangular prisms, or rods.

The abrasive article may be implemented such that the first set ofshaped abrasive particles is more than 60% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 0.5% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 1% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 2% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 5% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 10% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 15% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 20% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is 25% by weight or less of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the first and secondsets of shaped abrasive particles are the same size.

The abrasive article may be implemented such that the first and secondsets of shaped abrasive particles are different sizes.

The abrasive article may be implemented such that one of the first andsecond sets of abrasive particles are magnetically responsive.

The abrasive article may be implemented such that the abrasive articleis an abrasive belt or an abrasive disc.

An abrasive article is presented that includes a backing, a make coatlayer, and a plurality of shaped abrasive particles embedded within themake coat layer. The plurality of shaped abrasive particles include afirst plurality of shaped abrasive particles in a primary orientation.The primary orientation is an abrading orientation such that the firstplurality of shaped abrasive particles are oriented with a cuttingportion facing away from the backing. The plurality of shaped abrasiveparticles also include a second plurality of shaped abrasive particlesin a secondary orientation. The secondary orientation is a stabilizingorientation such that the second plurality of shaped abrasive particlesare oriented with a cutting portion facing toward the backing.

The abrasive article may be implemented such that the primaryorientation is at least 60% of the plurality of shaped abrasiveparticles by weight and wherein the secondary orientation is between0.5% and 25% of the plurality of shaped abrasive particles by weight.

The abrasive article may be implemented such that the first plurality ofshaped abrasive particles are aligned with respect to each other.

The abrasive article may be implemented such that aligned includescorresponding faces of a first shaped abrasive particle and a secondshaped abrasive particle being parallel.

The abrasive article may be implemented such that the first and secondplurality of particles are the same shape.

The abrasive article may be implemented such that the first and secondplurality of particles are different shapes.

The abrasive article may be implemented such that the first and secondplurality of particles are the same size.

The abrasive article may be implemented such that the first and secondplurality of particles are different sizes.

The abrasive article may be implemented such that the first plurality ofshaped abrasive particles each have a base, and the bases of adjacentshaped abrasive particles are substantially parallel.

The abrasive article may be implemented such that the shape of each ofthe first and second sets of abrasive articles are selected from thegroup consisting of: triangular prisms, trapezoidal prisms,tetrahedrons, crescents, stars, rectangular prisms, or rods.

The abrasive article may be implemented such that the first set ofshaped abrasive particles is more than 60% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 0.5% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 1% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 2% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 5% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 10% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 15% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is at least 20% by weight of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that the second set ofshaped abrasive particles is 25% by weight or less of the first andsecond sets of shaped abrasive particles.

The abrasive article may be implemented such that one of the first andsecond sets of abrasive particles are magnetically responsive.

The abrasive article may be implemented such that the abrasive articleis an abrasive belt or an abrasive disc.

Objects and advantages of this disclosure are further illustrated by thefollowing non-limiting examples, but the particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this disclosure.

EXAMPLES

In the following examples, fibre disc samples were made in the same wayby hand using the specified minerals and alignment tools, including acircular plastic transfer tool consisting of a rectangular array oftriangular cavities, having geometries such as those described in FIGS.4A-4C of PCT Pat. Publ. No. WO 2015/100018 A1 (Adefris et al.). A makeresin consisting of 49% resole phenolic resin (obtained as GP 8339 R-23155B from Georgia Pacific Chemicals, Atlanta, Ga.), 41% calciummetasilicate (obtained as WOLLASTOCOAT from NYCO Company, Willsboro,N.Y) , and 10% water was used, along with a size resin consisting of 38%resole phenolic resin, 60% cryolite (Solvay Fluorides, LLC, Houston,Tex.), and 2% red iron oxide pigment. Discs were cured using a ramp upat 6 °/minute with stops at 70° for 45 minutes, 90° for 45 minutes, and105° for 3 hours after make application or 16 hours after sizeapplication. Discs were then ramped down to room temperature at 6 °/min.After curing, discs were flexed in 2 perpendicular directions and leftto condition in a humidity-controlled room for at least 3 days.

The discs were tested using either an automated test or an offhandbeveling test. For the automated testing, a consistent torque control(set up at 3.4 amps) method was used. For each test, a 1018-14 steel barmeasuring 1-inch (2.54-cm) by 1-inch (2.54-cm) was used as the testsubstrate (workpiece) with the surface to be abraded. The disc sample(7-inch (17.8-cm)) diameter disc with ⅞-inch (2.22-cm) diameter centerhole) was installed on a disc grinder together with a 7-inch Extra HardRed Ribbed back-up pad (available from 3M Company, St. Paul, Minnesota).The disc was run at 5000 revolutions per minute (rpm). The workpiece waspressed into the disc and moved from near-center (about 6.35 cm from thecenter) to the edge for four passes, and then near the end of the grindtime it was swung back and forth quickly against the edge of the disc.This grinding process took 15 seconds, which was defined as one cycle.The workpiece was then cooled and tested again. The cut (the weight lossof the workpiece after an individual cycle) and the cumulative cut (thecumulative weight loss of the workpiece) in grams was recorded aftereach cycle. The end point of the test was 40% of maximum cut, or 100 or300 cycles as specified in a given example. In the offhand testing, aright angle tool with an identical Extra Hard Red Ribbed back-up pad wasused to grind a roughly 45° angle bevel onto a ¾” thick sheet of 1018carbon steel alternately with flattening said bevel back out. A singlecycle involves repeating this pattern back and forth for 1 minute.Testing was done for 10 cycles, or until a disc no longer wasfunctional.

Example 1

Shaped abrasive particles were prepared according to the disclosure ofU.S. Pat No. 8,142,531 (Adefris et al.). The shaped abrasive particleswere prepared by molding alumina sol gel in equilateral triangle-shapedpolypropylene mold cavities of side length 0.11 inch (2.794 mm) and amold depth of 0.037 inch (0.931 mm).

The shaped abrasive particles were patterned on fibre discs using acircular plastic transfer tool consisting of a rectangular array oftriangular cavities, having geometries such as those described in FIGS.4A-4C of PCT Pat. Publ. No. WO 2015/100018 A1 (Adefris et al.) atdensities of 344 and 384 grains/in². Subsequently, the discs werebackfilled with 50 grit garnet, or with electrostatically coated shapedgrain of a lower aspect ratio (with additional 50 garnet as a finalbackfill). Sample details are shown in Table 1.

Table 1 Sample formulation details for Example 1 Sample Shaped GrainPatterning Density (grains/in2) Make (g) Mineral (g) Shaped grainBackfill (g) 50 garnet backfill (g) Size (g) 1 344 4.3 14.4 13.6 13.7 2384 4.4 16.8 12.2 14.3 3 344 4.3 14.4 3.5 10.7 14.2

Offhand bevel testing as described above was performed to evaluate thesethree samples, as well as 982C and 782C controls. Results are shown inFIGS. 9A and 9B. The experimental samples, in general, are shown to havesimilar performance by virtue of their identical mineral and similarpattern density. However, differences can be seen when consideringweight loss and grams cut/grams weight lost. In this case, Sample 3,with electrostatically coated shaped grain, is found to have the lowestweight loss and highest grams cut/grams weight lost of the experimentalsamples. This is also seen observationally, in that Sample 3 is the onlyof the experimental samples to not have bare backing visible at somelocation on the disc following this relatively high pressure testing.FIG. 9C reinforces the idea that this improvement in disc survivabilityis due to the upside down particles, showing that Sample 3 has about 14upside down grains/in². The other two samples shown have 0.2 g and 1.5 gshaped grain electrostatically coated, respectively, representing levelsof 1.5%, 11%, and 25% w/w of the second grain relative to the patternedshaped grain. Corresponding samples were also tested via the abovedescribed automated method, where even the low 1.5% electrostaticallycoated addition is seen to have very low weight loss at similar cutvalues.

Table 2 Automated testing results for three different levels ofelectrostatically coated shaped grain backfill onto patterned loweraspect ratio shaped grain No. Material Initial Cut (g) Max Cut Total Cut(g), Cycle 100 Weight Loss 4 0.2 g shaped grain backfill 20.85 28.862443 1.04 5 1.5 g shaped grain backfill 21.44 30.06 2511 1.38 6 3.6 gshaped grain backfill 21.61 27.6 2216 1.14

Example 2

Shaped abrasive particles were prepared according to the disclosure ofU.S. Pat No. 8,142,531 (Adefris et al.). The shaped abrasive particleswere prepared by molding alumina sol gel in equilateral triangle-shapedpolypropylene mold cavities of side length 0.11 inch (2.794 mm) and amold depth of 0.028 inch (0.711 mm).

The shaped abrasive particles were patterned on a fibre disc using acircular plastic transfer tool consisting of a rectangular array oftriangular cavities, having geometries such as those described in FIGS.4A-4C of PCT Pat. Publ. No. WO 2015/100018 A1 (Adefris et al.). Theoverall cavity densities were 160 cavities per square inch (24.8cavities /cm²), 264 cavities per square inch (40.9 cavities /cm²), and304 cavities per square inch (47.1 cavities/cm²). Subsequently, the sameshaped grain were electrostatically coated as backfill. The percentageof electrostatically coated shaped grains to precisely placed shapedgrains ranged from 20% to 250%, with total mineral weights ranging from9.3 to 16.8 g/disc. Additional 40 grit aluminum oxide (AO) backfill wasadded to some discs that were 12 g/disc total mineral weight or less.

Automated testing results are tabulated in Table 3. The 304 grains/in²samples had the highest total cut, but also very high weight loss. Ingeneral, weight loss was high for these samples across the board andthere was no clear performance differentiation with these relativelyhigh shaped grain backfill weights. One clear trend was that theaddition of further backfill in the form of 40 AO improved life, as seenby the higher g cut/g weight loss ratio in identical pairs of sampleswith and without this additional backfill. Peak counts and number ofupside down particles are shown in FIGS. 10A and 10B. Both measurescorrelated roughly to the total shaped grain mineral coat weight, thoughnot linearly and not predictably.

Table 3 Example 2 formulation and automated test data No. Shaped GrainPatterning Density (grains/in2). Make (g) Miner. (g) Shaped GrainBackfill (g) AO Backfill (g) Size (g) % Weight shaped backfill Total Cut(g) Max Cut (g) Total Cycles Weight Loss A 160 4.2 4.6 11.6 0 15.8 2523055 34.2 133 14.3 B 160 4.2 4.3 12.5 0 14.1 291 1892 31.4 76 16.8 C 1604,4 4.1 7.3 13.1 14.8 178 3662 35.0 165 4.6 D 160 4.3 4.6 7.3 0 14.2 1595089 35.5 236 7.8 E 160 4.2 4.2 5.1 9.9 14.4 121 2718 33.7 131 5.3 F 1604.2 4.7 4.9 9.7 14.5 104 3310 35.7 151 4.7 G 264 4.3 8.2 8.4 0 15.1 1026668 33.2 300 12.5 H 264 4.2 8.4 8.8 0 14 105 2913 33.1 117 15.4 I 2644.3 8.3 4 8.2 14 48 4182 37.3 186 5.9 J 264 4.2 8.2 4.1 0 14.2 50 127938.2 42 6.0 K 264 4.3 7.8 1.7 8.4 14.2 22 3174 35.2 145 3.6 L 264 4.28.4 2 8.9 14 24 4292 37.2 186 3.6 M 304 4.2 10 6.9 0 14.3 69 6360 34.7300 9.6 N 304 4.3 9.6 6.6 0 14.7 69 6165 35.2 300 11.7 O 304 4.2 9.9 28.2 15.2 20 4992 34.7 242 3.9 P 304 4.3 10 2.2 0 14.1 22 4262 40.8 1775.7

Example 3

Shaped abrasive particles were prepared according to the disclosure ofU.S. Pat No. 8,142,531 (Adefris et al.). The shaped abrasive particleswere prepared by molding alumina sol gel in equilateral triangle-shapedpolypropylene mold cavities of side length 0.11 inch (2.794 mm) and amold depth of 0.037 inch (0.931 mm) were patterned on a fibre disc usinga circular plastic transfer tool consisting of a rectangular array oftriangular cavities, having geometries such as those described in FIGS.4A-4C of PCT Pat. Publ. No. WO 2015/100018 A1 (Adefris et al.) at adensity of 384 grains/in². Subsequently, equilateral triangle shapedgrains of height about 762 microns were electrostatically coated asbackfill. The backfill was electrostatically coated at 12.5%, 25%, and35% of total patterned mineral weight, for total mineral weights ofabout 17.2 g, 19.4 g, and 21.6 g. Additional 50 garnet backfill wasadded to all discs.

Automated testing results are tabulated in Table 4. 25% (4 g 762 micronequilateral triangle backfill) seems to be a tipping point forperformance, as total cut begins to decrease and weight loss increasesgoing to 35%. 12.5% (2 g of backfill) does not see the benefit of asmuch reinforcement, and thus has higher weight loss. Although itsinitial cut and total at cycle 100 are higher than the others, this isexpected with a more open mineral coat. This 12.5% sample would not beexpected to hold up as well in higher pressure testing as the 25% and35% samples due to the higher weight loss.

Table 4 Automated testing results of three levels of electrostaticallycoated shaped grain backfill of smaller height No. Backfill (g) InitialInitial (7-10) Max Cycle Max Cut Cycle 100 Total Cyc100 In. Wt Fin. WtSlope Wt loss A 2 22.55 126.3 9 34.1 23.3 2770 68.95 66.26 -0.119 2.69 B4 21.17 122.7 4 35.4 22.5 2684 70.73 69.21 -0.134 1.52 C 6 23.21 116.3 630.8 24.7 2608 72.38 70.57 -0.064 1.81

Example 4

Shaped abrasive particles were prepared according to the disclosure ofU.S. Pat No. 8,142,531 (Adefris et al.). The shaped abrasive particleswere prepared by molding alumina sol gel in equilateral triangle-shapedpolypropylene mold cavities of side length 0.11 inch (2.794 mm) and amold depth of 0.037 inch (0.931 mm). These grains were patterned on afibre disc a circular plastic transfer tool consisting of a rectangulararray of triangular cavities, having geometries such as those describedin FIGS. 4A-4C of PCT Pat. Publ. No. WO 2015/100018 A1 (Adefris et al.)at densities of 160 and 304 grains/in². Subsequently, equilateraltriangle shaped grains of height about 762 microns wereelectrostatically coated as backfill. The backfill was electrostaticallycoated at 10-110% of total patterned mineral weight, for total mineralweights of about 18.6 g for the 304 grains/in² density, and about 9.6 gfor the 160 grains/in² density.

Automated testing results for Example 4 are shown in Table 5. The two304 grains/in² discs have moderate weight loss and total cut values,indicating some degree of reinforcement from the ~110% w/w smallershaped grains coated, relative to the patterned mineral. However, the~100% w/w addition of grains to the 160 linear samples is insufficientto overcome this very low mineral coating weight, thus leading to highweight loss.

Table 5 Formulation and automated test results for Example 4 No ShapedGrain Patterning Density (grains/in2) Mak e (g) Miner al (g) Backfi 11(g) Size (g) Initial Cut (g) Weigh t loss (g) Total Cycle s Total Cut(g) A 304 4.6 8.8 9.6 18. 4 28.5 2.82 203 4699 B 304 4.5 8.8 9.9 19 28.12.74 150 3427 C 160 3.3 6 6.1 12. 1 32.7 9.82 149 3570 D 160 3.5 5.9 6.213. 9 33.5 7.56 300 6599

All cited references, patents, and patent applications in the aboveapplication for letters patent are herein incorporated by reference intheir entirety in a consistent manner. In the event of inconsistenciesor contradictions between portions of the incorporated references andthis application, the information in the preceding description shallcontrol. The preceding description, given in order to enable one ofordinary skill in the art to practice the claimed disclosure, is not tobe construed as limiting the scope of the disclosure, which is definedby the claims and all equivalents thereto.

1. An abrasive article comprising: a first set of shaped abrasiveparticles, wherein a majority of the first set of shaped abrasiveparticles are oriented with respect to a backing in a first orientation;a second set of shaped abrasive particles, wherein a majority of thesecond set of shaped abrasive particles are oriented with respect to thebacking in a second orientation, and wherein the second orientationdiffers from the first orientation; and wherein the first and second setof shaped abrasive particles are embedded within a make coat layer onthe backing.
 2. The abrasive article of claim 1, wherein each of thefirst set of shaped abrasive particles includes a base portion and anabrading portion, and wherein the base portion is embedded within themake coat layer and the abrading portion faces away from the backing. 3.The abrasive article of claim 1, wherein some of the second set ofshaped abrasive particles are oriented at least 90° with respect to themajority of the first set of shaped abrasive particles.
 4. The abrasivearticle of claim 1, wherein the majority of the second set of shapedabrasive particles are oriented up to 180° with respect to the majorityof the first set of shaped abrasive particles.
 5. The abrasive articleof claim 1, and further comprising a third set of abrasive particlesforming a closed coat on the backing.
 6. The abrasive article claim 1,wherein the first set of shaped abrasive particles are oriented withrespect to each other, such that faces of adjacent abrasive particlesare parallel.
 7. The abrasive article of claim 6, wherein the second setof shaped abrasive particles is at least 5% by weight of the first andsecond sets of shaped abrasive particles.
 8. The abrasive article ofclaim 1, wherein one of the first and second sets of abrasive particlesare magnetically responsive.
 9. The abrasive article of claim 1, whereinthe first set of shaped abrasive particles comprise: a shape selectedfrom the group consisting of: rods, tetrahedrons, right angle triangularprisms, isosceles triangular prisms, equilateral triangular prisms,scalene triangular prisms, trapezoidal prisms, crescents, stars, cubes,dual tapered, irregular polygonal faces, shape-on-shape, variablecross-sectional area; or a feature selected from the group consistingof: a sloping sidewall, a groove, a recess, a facet, a fracturedsurface, a cavity, more than one vertex, sharp edges, a non-shapedportion, a notch, a rake angle and / or a low roundness factor.
 10. Amethod of making a coated abrasive article, the method comprising:coating a backing with a coating precursor layer; embedding a first setof abrasive particles within the make coat precursor, wherein a majorityof the first set of abrasive particles have a first orientation withrespect to the backing and are oriented such that faces of adjacentparticles are parallel to each other; embedding a second set of abrasiveparticles within the coating precursor layer, wherein a majority of thesecond set of abrasive particles have a second orientation with respectto the backing; and curing the coating precursor layer.
 11. The methodof claim 10, wherein the coating precursor layer is a make coat, andwherein the method also comprises applying a size coat over at least oneof the first and second sets of abrasive particles.
 12. The method ofclaim 10, wherein the coating precursor layer is a size coat, andwherein the method also includes applying a make coat to the backing.13. The method of claim 12, wherein the first set of abrasive particlesare embedded within the make coat, and wherein the second set ofabrasive particles are embedded within the size coat.
 14. The method ofclaim 10, and further comprising embedding a third set of abrasiveparticles within the make coat precursor.
 15. The method of claim 14,and wherein the third set of abrasive particles are crushed abrasiveparticles.
 16. The method of claim 10, and further comprising: fillingan alignment tool with the first set of abrasive particles such that aplurality of cavities within the alignment tool receive one of the firstset of abrasive particles; and positioning the alignment tool such thateach of the first set of abrasive particles move out of the plurality ofcavities and embed within the make coat.
 17. The method of claim 10,wherein the first set of abrasive particles are magnetically responsive,and wherein embedding the first set of abrasive particles within themake coat precursor comprises exposing the first set of abrasiveparticles to a magnetic field such that the first set of abrasiveparticles move into the first orientation.
 18. The method of claim 10,wherein embedding the second set of abrasive particles within the makecoat precursor comprises drop coating the second set of abrasiveparticles, wherein the first orientation comprises the first set ofabrasive particles aligned in rows on the backing, and wherein thesecond orientation comprises each of the second set of abrasiveparticles embedding into the make coat in a space between a first rowand a second row of the first set of abrasive particles.
 19. The methodof claim 10, wherein the first set of abrasive particles are shaped asone of: triangular prisms, rods, tetrahedrons, crescents, stars, cubes,rectangular prisms, or another regular polygonal prism.
 20. An abrasivearticle comprising: a backing; a coating layer applied to the backing; afirst set of shaped abrasive particles, each of the first set of shapedabrasive particles comprising a first base edge and a first cuttingportion, wherein the first set of shaped abrasive particles are in afirst orientation comprising the first base edge embedded within thecoating layer and the first cutting portion oriented away from thebacking; and a second set of shaped abrasive particles, each of thesecond set of shaped abrasive particles comprising a second base edgeand a second cutting portion, wherein the second set of shaped abrasiveparticles are in a second orientation comprising the second cuttingportion embedded within the coating layer and the first base edge facingaway from the backing. 21-37. (canceled)